Removed `#rabbit_server` method

This was a mistake on my part adding this method.  The rabbit-host
directive takes a host, not a host and port.  We are going to lock
0.3.0 version of this library Monday, and not add any minor features.
Wanted to delete this confusing method, before we lock this version
down.

Change-Id: Ibc48fc267f2b0a1ee83963f49818edbd67adaca2
Add common messaging attributes

Similar to the way in which we handle database attributes, provide a
mechanism that allows for centralized messaging configuration. Right
now this supports rabbit, but there is no reason other message queues
could not be added in the default['openstack']['mq'] namespace.

Change-Id: Id9d34fa7c256920dd575eee57c7b3820dacf8068
Merge "Add common messaging attributes"
Correct faulty Chef search query

The search returns a Hash, not a list, so we need
to remove the reference to [0] in the memcached_servers
library routine call otherwise you get:

undefined method `[]' for nil:NilClass

in chef-client runs.

Change-Id: I479aca833a2eb80fa2baf3e54809b2edaa713b89
Merge "Correct faulty Chef search query"